It is known that heat-treatment is invalid to Staphylococcus aureus diarrhea toxin and Bacillus cereus emetic toxin among bacterial toxins that contaminate into foods to cause food poisoning because they are heat resistant toxins. As to Staphylococcus aureus toxin that is extremely important in food hygiene, the detection method thereof is established. Meanwhile, any appropriate methods of detecting Bacillus cereus emetic toxin have never been developed to date. Since Bacillus cereus forms spores that are resistant to heating at 100° C. for 30 minutes, it is difficult to perfectly kill them by boiling. Therefore, contamination due to Bacillus cereus emetic toxin is a problem not only in unheated foods but also in heated foods. Bacillus cereusis known worldwide as a bacterium causing food poisoning, and also in Japan, many food poisoning cases due to this bacterium has been reported. In 1994, the emetic toxin (named as “cereulide”) was isolated and purified from Bacillus cereus and the chemical structure thereof was determined (Agata, N., et al FEMS Microbiol. Lett. 121, 31-34 (1994)). Accordingly, a method of detecting cereulide by using HEp-2 cells was developed (Agata, N., et al FEMS Microbiol. Lett. 121, 31-34 (1994)).
Herein, clarifying the presence of an emetic toxin (cereulide) in foods and other specimens is very important in management of food manufacture according to HACCP, and the development of methods of detecting thereof has been demanded worldwide. However, any methods of carrying out detection of Bacillus cereus and detection of cereulide simply and rapidly have never been developed to date. Since the method using HEp-2 cells as mentioned above also requires skilled technique and has difficulty in simple and rapid detection and in treating a large number of specimens simultaneously. Furthermore, in a case where the specimen is vomit, feces, foods or smear samples of a patient, before identification of Bacillus cereus, procedures from enrichment culture, isolation culture through pure culture and confirmatory culture have to be carried out. Each culture step needs 18 to 24 hours and about no less than 4 days in total time required.
The present invention has been made under the above-mentioned circumstances, it is an object of the present invention to provide polypeptide and nucleic acid, etc. that can be used for detecting cereulide, and a method of rapidly detecting cereulide using the polypeptide and nucleic acid, etc.